I had an idea about an SCP involving something like a lucky penny, or nickel. The idea is that it's small enough to be unnoticeable, and having it be currency adds to the potential story. How it works, is while in possession of it, a person becomes really lucky, brilliant right?

Anyway, I figured that was a bit plain by itself so I was thinking that it should have some kind of repercussions for getting used. For instance, because it's based of a penny/currency it could bring luck for money, but bad luck for other things. The owner gets rich, but friends and family mysteriously suffer kind of setting. Another backlash could be that when the owner spends/looses the coin, they become super unlucky. I'm not really going for the 'horror' vibe with this, just more of a supernatural/don't mess with it one. Like, it's super useful, but also dangerous.

Also anything to spice up the containment could be interesting, because it's just a coin so it could just get tossed in a box and ignored.

How would someone be able to define good/bad luck from a scientific standpoint?

Also, I'm pretty sure that this "good/bad luck" object has been pitched a bunch of times, usually as coins. Why would the coin exist? What is its purpose? Right now, you have an object with a clearly defined activation and function, with no context or backstory, essentially a generic magic object.